.wrapper {
        width: 100%;
        height: 720px;
        display: table;
    }   
 
    .main {
        display: table-cell;
        vertical-align: middle;
        text-align: center;
    }
 
    .quiz-frame {
        border: 0;
        box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
    }
 
    .quiz__head {
        font-size: 20pt;
        margin: 10px;
        margin-bottom: 20px;
    }
    
    .head__content {
        padding: 5px;
    }
    
    .quiz__body {
        margin: 10px;
    }
    
    .button {
        border: 0;
        border-radius: 15px;
        background: #6477EB;
        color: #fff;
        padding: 15px 25px;
        width: 30%;
        font-size: 15pt;
        display: block;
        margin: 2px auto;
        cursor: pointer;
    }

    h3 {
        margin: 0;
    }

    a {
        margin: 0;
        font-size: 30px;
    }
    
    .button_wrong {
        background: #EB6465;
    }
    
    .button_correct {
        background: #5EB97D;
    }
    
    .button_passive {
        background: #B3B3B3;
    }


    @media screen and (max-width: 400px) {
        
        .quiz__head {
            font-size: 18px;
        }

        .button {
            width: 70%;
            font-size: 13px;
        }
    }

    @media screen and (max-width: 1100px) {
        
        .quiz__head {
            font-size: 22px;
        }

        .button {
            width: 40%;
            font-size: 17px;
        }
    }

    @media screen and (max-width: 600px) {
        
        .quiz__head {
            font-size: 20px;
        }

        .button {
            width: 50%;
            font-size: 15px;
        }
    }

    @media screen and (max-width: 300px) {
        
        .quiz__head {
            font-size: 18px;
        }

        .button {
            width: 70%;
            font-size: 13px;
        }
    }